MATLAB: How to plot a conditional function

conditionif statementplot

I am trying to combine logarithmic (BH2) and polynomial (BH1) trendlines into a blended trendline (BH3) that passes through the origin. My current code plots BH3 for the final condition for all t. Please could someone offer corrected code? Here are functions and problematic code is below. Many thanks in advance.
  • BH1: y = 7.1851*ln(t)-2.62
  • BH2: y = -0.06*t^2+2.185*t
  • BH3: 0<t<=3.07 y= BH2 3.07<t<=7.92 y= 0.67*BH2+0.33*BH1 t>7.92 y= 0.5*BH1+0.5*BH2
t = 0:0.5:30; %define time vector
BH1 = 7.81*log(t)-2.625; %define logarithmic trend 
BH2 = -0.06*t.^2+2.19*t; %define polynomial trend
 %now define combination of trends
if t <= 3.07 %force through origin
BH3 = BH2; 
elseif 3.07 < t <= 7.92; %intial blend
    BH3 = 0.67*BH2 + 0.33*BH1;
else %equal blend
    BH3 = 0.5*BH2 + 0.5*BH1;
end
 plot(t,BH1,'r',t,BH2,'r',t,BH3,'b');

Best Answer

   t2 = 3.07 < t & t <= 7.92; % EDIT
   t3 = t > 7.92;
   BH3 = BH2;
   BH3(t2) = BH3(t2)*.67 + BH1(t2)*.33;
   BH3(t3) = BH3(t3)*.5 + BH1(t3)*.5;
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